This investigation is open label, with treatment assignment to one of two groups at the investigator's discretion. Subjects will be eligible for this protocol if they had previously been entered at the same site into one of the following trials. M/3331/0003, M/3331/0013, M/331/0017, M/331/0018, M/3331/0021, and M/3331/0022. Patients participating in blinded trials will not have blind broken from their previous trial before entering into this protocol. The treatment regimen of each drug for this protocol will be the number of tablets or capsules the patient was taking in their previous trial. An addition of new agent will be dosed at the recommended dosage level. For patient to enter and remain in this study, they will need to maintain a minimum dosage level of 100mg tid delavirdine, 100mg TID ZDV, 75 mg BID ddl and/or 0.0375 mg TID ddC.